In details

The cyanobacteria


Extremely bacterial, cyanobacteria are also prokaryotes. They are all photosynthesizing autotrophs, but their cells do not have chloroplasts. Chlorophyll like a, is dispersed by the hyaloplasma and photosynthesizing coverslips, which are ramifications of the plasma membrane.

In addition to chlorophyll, they have other accessory pigments, such as carotenoids (carrot carotene-like pigments), phycoerythrin (a red pigment typical of the cyanobacteria found in the Red Sea) and the phycocyanin (a bluish-colored pigment that gave its name to cyanobacteria, formerly called "blue algae"). They live in the sea, in fresh water and in humid land.

There are species that have isolated cells and others that form colonies of different shapes.

Reproduction in cyanobacteria

In unicellular cyanobacteria, asexual reproduction occurs by binary cell division. In filamentous species, filament fragmentation is common, producing several genetically similar offspring. These cell-containing fragments are called homogons.

Archaebacteria and Their Amazing Way of Living

Many authors have now considered it opportune to separate Archeobacteria (primitive bacteria) from so-called Eubacteria (true bacteria).

Based on biochemical studies (ribosomal RNA sequences, absence of muramic acid in the wall, membrane lipid composition), it was concluded that there are more than 3000 M.a. there would have been a divergence in the evolution of prokaryotic organisms, and two distinct lineages emerged.

So far no genetic recombination has been identified in this group of organisms. The branch that originated the archaebacteria would later have originated the eukaryotes.

The present archaebacteria are considered to have suffered little change from their ancestors. These prokaryotes live in places with extremely adverse to other living beings, probably similar to those that would exist on early Earth.

Archaeobacteria can be divided into three major groups:

  • Halophiles - live in extreme saline concentrations, dozens of times saltier than seawater, in places such as saline, salt or soda lakes, etc. Its optimum growth temperature is between 35 and 50ºC.

These bacteria are autotrophic, but their ATP production mechanism is radically different from usual because they use a unique red pigment - bacteriorhodopsin - which functions as a proton pump (such as mitochondrial oxidative phosphorylation) that gives them energy;

  • Methanogeneas - This group of bacteria was the first to be recognized as unique. They live in marshes, ocean floors, sewage treatment plants and the digestive tract of some herbivorous insect and vertebrate species where they produce methane (CH4) as a result of cellulose degradation.

The known natural gas reserves are the result of obligatory anaerobic metabolism and methane production of bacteria of this type in the past. Some can produce methane from CO2 and H2, getting energy from that process.

The gender Methanosarcina can fix atmospheric nitrogen, a capacity that was once considered unique to eubacteria;

  • Thermoacidophils -live in acidic thermal water zones, with optimum temperatures between 70 and 150ºC and optimum pH values ​​close to 1. Most of them metabolize sulfur: they can be autotrophic, obtaining energy from the formation of hydrogen sulfide (H2S) from sulfur, or heterotrophic.